U.S. patent application number 13/095225 was filed with the patent office on 2011-11-03 for radio communication apparatus and packet forwarding method.
This patent application is currently assigned to FUJITSU LIMITED. Invention is credited to Hiroshi FUJITA.
Application Number | 20110268030 13/095225 |
Document ID | / |
Family ID | 44858202 |
Filed Date | 2011-11-03 |
United States Patent
Application |
20110268030 |
Kind Code |
A1 |
FUJITA; Hiroshi |
November 3, 2011 |
RADIO COMMUNICATION APPARATUS AND PACKET FORWARDING METHOD
Abstract
A radio communication apparatus including: a radio communication
interface; and a processor; the processor being configured to
detect a first radio communication apparatus and a second radio
communication apparatus based on a piece of address information
received by the radio communication interface; and to select one of
a first layer and a second layer as a forwarding layer, in which a
packet is forwarded to a next forwarding address according to the
radio communication apparatus of the next forwarding address
corresponding to a destination address of the packet.
Inventors: |
FUJITA; Hiroshi; (Kawasaki,
JP) |
Assignee: |
FUJITSU LIMITED
Kawasaki-shi
JP
|
Family ID: |
44858202 |
Appl. No.: |
13/095225 |
Filed: |
April 27, 2011 |
Current U.S.
Class: |
370/328 |
Current CPC
Class: |
H04W 40/02 20130101;
H04L 45/123 20130101 |
Class at
Publication: |
370/328 |
International
Class: |
H04W 40/02 20090101
H04W040/02 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 30, 2010 |
JP |
2010-105433 |
Claims
1. A radio communication apparatus comprising: a radio
communication interface configured to transmit or receive radio
signals; and a processor configured to control the radio
communication interface to forward a packet to a next forwarding
destination in a first layer; to control the radio communication
interface to forward the packet to the next forwarding destination
in a second layer which is higher than the first layer; to control
the radio communication interface to receive a piece of address
information of another radio communication apparatus in the first
layer from a first radio communication apparatus as the other radio
communication apparatus which forwards the packet in the first
layer; to control the radio communication interface to receive the
piece of address information of the other radio communication
apparatus in the second layer from the first radio communication
apparatus and receives the piece of the address information of the
radio communication apparatus of a second type in the second layer
from a second radio communication apparatus which forwards the
packet in the second layer; to detect the first radio communication
apparatus and the second radio communication apparatus based on the
piece of address information received by the radio communication
interface; and to select one of the first layer and the second
layer as a forwarding layer, in which the packet is forwarded to a
next forwarding address according to the radio communication
apparatus of the next forwarding address corresponding to a
destination address of the packet.
2. The radio communication apparatus according to claim 1, wherein
the processor is further configured to control the radio
communication interface to receive a piece of path information from
the first radio communication apparatus and the second radio
communication apparatus; and to generate a piece of forwarding
destination information that specifies the next forwarding address
corresponding to the destination address of the packet based on the
received piece of path information; and the piece of path
information includes a piece of address information of the radio
communication apparatus as a transmission source of the piece of
path information and the destination address by which the packet
may be forwarded from the radio communication apparatus as the
transmission source.
3. The radio communication apparatus according to claim 2, wherein
the processor is further configured to determine the next
forwarding destination based on a path cost which varies depending
on whether a forwarding layer of the packet is one of the first
layer and the second layer.
4. The radio communication apparatus according to claim 3, wherein
the processor is further configured to determine the next
forwarding address based on the number of hops in the path when the
path costs of a plurality of paths are equal.
5. The radio communication apparatus according to claim 1, wherein;
the processor is further configured to control the radio
communication interface to receive the packet; and to determine
whether the received packet is forwarded in one of the first layer
and the second layer according to a value of a header of the
received packet.
6. The radio communication apparatus according to claim 1, wherein
when the packet is forwarded in the first layer, the processor is
configured to store the destination address of the second layer in
the header of the first layer to a memory.
7. A forwarding method of a packet which is performed by a radio
communication apparatus, comprising: receiving a piece of address
information of the first radio communication apparatus in the first
layer from the first radio communication apparatus as another radio
communication apparatus which selects one of the first layer and
the second layer which is higher than the first layer as a layer in
which the packet is forwarded; receiving the piece of address
information, from the first radio communication apparatus, of the
other radio communication apparatus in the second layer, and the
piece of address information, from the second radio communication
apparatus which forwards a packet in the second layer, of the
second radio communication apparatus in the second layer; detecting
the first radio communication apparatus and the second radio
communication apparatus based on the received piece of address
information; selecting one of the first layer and the second layer
as the layer in which the packet is forwarded to the next
forwarding address according to the radio communication apparatus
of the next forwarding address which is specified for the
destination address of the packet; and forwarding the packet in the
selected layer to the next forwarding address.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from the prior Japanese Patent Application No. 2010-105433
filed on Apr. 30, 2010, the entire contents of which are
incorporated herein by reference.
FIELD
[0002] The embodiments discussed herein are related to a radio
communication apparatus and a packet forwarding method of a
packet.
BACKGROUND
[0003] In an ad hoc communication, a multi-hop communication is
performed to send a packet to a radio communication apparatus as a
final destination when a radio communication apparatus relays a
packet that is transmitted from another radio communication
apparatus. In a conventional technique, packet forwarding
processing in the multi-hop communication is performed in a layer
that manages routing processing, for example, a layer 3 of Open
System Interconnection (OSI) reference model.
[0004] There is a proposal of a radio communication network in
which a radio communication apparatus 31, which includes a
forwarding module belonging to a Media Access Control (MAC) layer
that is lower than an Internet layer, forwards a packet by the
multi-hop communication.
PATENT DOCUMENT
[0005] [Patent Document 1] Japanese Laid-open Patent Publication
No. 2008-17028 [0006] [Patent Document 2] International Patent
Publication No. WO2006/129863
SUMMARY
[0007] According to an aspect of the invention, a radio
communication apparatus including: a radio communication interface
configured to transmit or receive radio signals; and a processor
configured to control the radio communication interface to forward
a packet to a next forwarding destination in a first layer; to
control the radio communication interface to forward the packet to
the next forwarding destination in a second layer which is higher
than the first layer; to control the radio communication interface
to receive a piece of address information of another radio
communication apparatus in the first layer from a first radio
communication apparatus as the other radio communication apparatus
which forwards the packet in the first layer; to control the radio
communication interface to receive the piece of address information
of the other radio communication apparatus in the second layer from
the first radio communication apparatus and receives the piece of
the address information of the radio communication apparatus of a
second type in the second layer from a second radio communication
apparatus which forwards the packet in the second layer; to detect
the first radio communication apparatus and the second radio
communication apparatus based on the piece of address information
received by the radio communication interface; and to select one of
the first layer and the second layer as a forwarding layer, in
which the packet is forwarded to a next forwarding address
according to the radio communication apparatus of the next
forwarding address corresponding to a destination address of the
packet.
[0008] The object and advantages of the invention will be realized
and attained by at least the features, elements and combinations
particularly pointed out in the claims. It is to be understood that
both the foregoing general description and the following detailed
description are exemplary and explanatory and are not restrictive
of the invention, as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a diagram illustrating an example of a
configuration of a network;
[0010] FIG. 2 is a diagram illustrating a hardware configuration
example of a radio communication apparatus;
[0011] FIG. 3 is a diagram illustrating a first configuration
example of a radio communication apparatus of a first type;
[0012] FIG. 4 is a diagram illustrating a first example of
forwarding address information;
[0013] FIG. 5 is a diagram illustrating a second example of the
forwarding address information;
[0014] FIG. 6 is an explanatory diagram of a header format of a
packet of a first layer;
[0015] FIG. 7 is a diagram illustrating a configuration example of
a radio communication apparatus of a second type;
[0016] FIG. 8 is an explanatory diagram of a first example of
processing of the radio communication apparatus of the first
type;
[0017] FIG. 9 is an explanatory diagram of an example of
determining processing of a forwarding address and a forwarding
layer;
[0018] FIG. 10 is a diagram illustrating a second configuration
example of the radio communication apparatus of the first type;
[0019] FIG. 11 is a diagram illustrating a third configuration
example of the radio communication apparatus of the first type;
[0020] FIG. 12 is an explanatory diagram of a second example of the
processing of the radio communication apparatus of the first
type;
[0021] FIG. 13 is an explanatory diagram of a first example of
generating processing of the forwarding address information;
[0022] FIG. 14 is an explanatory diagram of an example of the
generating processing of the forwarding address information and the
determining processing of the forwarding layer;
[0023] FIG. 15 is an explanatory diagram of a second example of the
generating processing of the forwarding address information;
and
[0024] FIG. 16 is a diagram illustrating a fourth configuration
example of the radio communication apparatus of the first type.
DESCRIPTION OF EMBODIMENTS
[0025] In a multi-hop communication, a packet may be forwarded in a
layer that is lower than a layer that manages routing processing.
Hereinafter, the layer that manages the routing processing is
referred to as a "layer A," and the layer that is lower than the
layer A is referred to as a "layer B." The layer B is lower than
the layer A. Thus, when a packet is forwarded in the layer B,
processing delay is reduced compared to the multi-hop communication
where the packet is forwarded in the layer A.
[0026] However, a communication protocol used for the packet
forwarding in the layer B is different from the communication
protocol used for the packet forwarding in the layer A. Therefore,
a network that includes both the conventional radio communication
apparatus that supports simply the packet forwarding in the layer A
and the radio communication apparatus that supports the packet
forwarding in the layer B may not be configured. Thus, in the
multi-hop communication network, the packet forwarding in the layer
A may not be present with the packet forwarding at a higher speed
in the layer B.
[0027] An aspect of the embodiments is to realize a multi-hop
communication in which packet forwards in a plurality of layers are
performed.
[0028] The embodiments of the invention will be described below
with reference to the attached diagrams. FIG. 1 is a diagram
illustrating an example of a configuration of a network. A network
1 includes radio communication apparatuses 10-a, and 10-1 to 10-5.
The network 1 is a multi-hop network in which a packet is
transmitted by the multi-hop communication between a radio
communication apparatus as a packet transmission source and another
radio communication apparatus as a packet destination.
[0029] A line used to couple the radio communication apparatuses
10-a and 10-1 to 10-5 indicates a path through which a packet is
forwarded between the radio communication apparatuses while the
packet is forwarded from the radio communication apparatus 10a to
the radio communication apparatus as the packet destination. For
example, the packet is transmitted from the radio communication
apparatus 10-a as the transmission source to the radio
communication apparatus 10-2 as the destination through the radio
communication apparatus 10-1. For example, the packet is
transmitted from the radio communication apparatus 10-a as the
transmission source to the radio communication apparatus 10-5 as
the destination through the radio communication apparatus 10-3.
[0030] In the network 1, the radio communication apparatus of the
first type is present with the radio communication apparatus of the
second type. The radio communication apparatus of the first type
may perform forwarding processing of a packet in the first layer or
the second layer. On the other hand, the radio communication
apparatus of the second type performs the forwarding processing of
the packet in the second layer and does not have a forwarding
function of the packet in the first layer. The first layer is lower
than the second layer. For example, the first layer and the second
layer are the layer 2 and the layer 3 in the OSI reference model,
respectively.
[0031] In the example illustrated in FIG. 1, the radio
communication apparatuses 10-a, 10-1, 10-2, and 10-5 are radio
communication apparatuses of the first type, and radio
communication apparatuses 10-3 and 10-4 are radio communication
apparatuses of the second type.
[0032] FIG. 2 is a diagram illustrating a hardware configuration
example of the radio communication apparatus 10-a of the first
type. The radio communication apparatuses 10-1 to 10-5 have a
hardware configuration equivalent to the radio communication
apparatus 10-a. The radio communication apparatus 10-a includes a
processor 20, a memory 21, an auxiliary storage device 22, and a
radio communication unit 23. The processor 20, the memory 21, the
auxiliary storage device 22, and the radio communication unit 23
are coupled with each other by a bus 24 through which data is
transmitted.
[0033] The auxiliary storage device 22 stores various computer
programs and data used to control operations of the radio
communication apparatus 10-a. The auxiliary storage device 22 may
include a hard disk, a nonvolatile memory, and the like. The
processor 20, which is a data processing device, executes a program
stored in the auxiliary storage device 22 and performs various
processing for controlling the operations of the radio
communication apparatus 10-a. The memory 21 stores a program that
is being executed by the processor 20 and data that is temporally
used by the program. The radio communication unit 23 is a radio
communication interface that performs radio communication
processing of a radio signal among the radio communication
apparatuses 10-1 to 10-5.
[0034] The hardware configuration illustrated in FIG. 2 is an
example of the hardware configuration of the radio communication
apparatuses 10-a, and 10-1 to 10-5. Various types of hardware
configurations, which perform the processing described below, are
applicable to the radio communication apparatuses 10-a and 10-1 to
10-5.
[0035] FIG. 3 is a diagram illustrating a first configuration
example of the radio communication apparatus 10-a of the first
type. The processing performed by components of the radio
communication apparatus 10-a is realized if the processor 20
executes a forwarding program stored in the auxiliary storage
device 22 illustrated in FIG. 2. FIG. 3 illustrates mainly
functions related to explanation of this embodiment. The radio
communication apparatus 10-1, 10-2, and 10-5 of the first type may
have configurations equivalent to the radio communication apparatus
10-a. The other embodiments have the similar configurations.
[0036] The radio communication apparatus 10-a of the first type
includes a transmitting unit 30, a receiving unit 31, a first
forwarding unit 32, a first layer packet generating unit 33, a
second forwarding unit 34, and a second layer packet generating
unit 35. The radio communication apparatus 10-a includes a first
address receiving unit 36, a second address receiving unit 37, a
detecting unit 38, a forwarding address storage unit 39, a
forwarding layer selecting unit 40, and a path determining unit
41.
[0037] The transmitting unit 30 transmits a packet to another radio
communication apparatus. The receiving unit 31 receives the packet
transmitted from the other radio communication apparatus. The first
forwarding unit 32 obtains a data part from the received packet and
outputs the data part to the first layer packet generating unit 33.
Alternatively, the first forwarding unit 32 outputs the data, which
is stored in the packet transmitted from the radio communication
apparatus 10-a as the transmission source, to the first layer
packet generating unit 33.
[0038] Furthermore, the first forwarding unit 32 performs the
forwarding processing for forwarding the packet received from the
receiving unit 31 to the radio communication apparatus as the next
forwarding destination in the first layer. The first forwarding
unit 32 performs the forwarding processing in the first layer for
transmitting the packet transmitted from the radio communication
apparatus 10-a as the transmission source to the radio
communication apparatus as the next forwarding destination.
[0039] In the forwarding processing, the first forwarding unit 32
obtains, from the path determining unit 41, the forwarding address
in the first layer according to the destination address of the
packet from the path determining unit 41. The forwarding address is
an address of the radio communication apparatus to which the packet
is forwarded after being forwarded to the radio communication
apparatus 10-a.
[0040] Hereinafter, the packet forwarded in the first layer is
referred to as a "first layer packet," and the address used in the
first layer is referred to as a "first layer address." Furthermore,
the packet forwarded in the second layer is referred to as a
"second layer packet," and the address used in the second layer is
referred to as a "second layer address."
[0041] The first layer packet generating unit 33 generates a
header, which includes at least a destination address and a
forwarding address, and a packet, which stores the data received
from the first forwarding unit 32. The generated first layer packet
is transmitted by the transmitting unit 30.
[0042] The second forwarding unit 34 obtains the data part from the
received packet and outputs the data part to the second layer
packet generating unit 35. Alternatively, the second forwarding
unit 34 outputs the data, which is stored in the packet transmitted
from the radio communication apparatus 10-a as the transmission
source, to the second layer packet generating unit 35. The second
forwarding unit 34 performs the forwarding processing for
forwarding the packet received by the receiving unit 31 to the
radio communication apparatus as the next forwarding destination.
Furthermore, the second forwarding unit 34 performs the forwarding
processing for forwarding the packet, which is transmitted from the
radio communication apparatus 10-a as the transmission source, to
the radio communication apparatus as the next forwarding
destination. In the forwarding processing, the second forwarding
unit 34 obtains, from the path determining unit 41, the forwarding
address in the second layer according to the destination address of
the packet.
[0043] The second layer packet generating unit 35 generates a
packet that stores a header that includes at least the forwarding
address, the data obtained from the received packet by the second
forwarding unit 34 or the data to be transmitted from the radio
communication apparatus 10-a. The generated second layer packet is
encapsulated in the first layer packet by the first layer packet
generating unit 33 and is then transmitted by the transmitting unit
30.
[0044] The first address receiving unit 36 receives address
information related to the first layer address of the radio
communication apparatus of the first type in the network 1 from
another radio communication apparatus, for example, the radio
communication apparatuses 10-1, 10-2, or 10-5. For example, if the
transmission source of the address information is the radio
communication apparatus 10-1, the address information includes at
least the first layer address of the radio communication apparatus
10-1. If the transmission source of the address information is the
radio communication apparatus 10-1, the address information may
include the first layer address, which is detected by the radio
communication apparatus 10-1, of the radio communication apparatus
of the first type other than the radio communication apparatus
10-1.
[0045] The second address receiving unit 37 receives, from another
radio communication apparatuses, for example, one of the radio
communication apparatuses 10-1 to 10-5, the address information
related to the second layer address of the radio communication
apparatus in the network 1. For example, if the transmission source
of the address information is the radio communication apparatus
10-3, the address information includes at least the second layer
address of the radio communication apparatus 10-3. If the
transmission source of the address information is the radio
communication apparatus 10-3, the address information may include
the second layer address, which is detected by the radio
communication apparatus 10-3, of the radio communication apparatus
other than the radio communication apparatus 10-3.
[0046] Based on the address information received by the first
address receiving unit 36 and the second address receiving unit 37,
the detecting unit 38 detects the radio communication apparatuses
10-1, 10-2, and 10-5 of the first type and the radio communication
apparatuses 10-3 and 10-4 of the second type. For example, the
detecting unit 38 may detect the radio communication apparatus,
which has the first layer address, as the radio communication
apparatus of the first type. Furthermore, for example, the
detecting unit 38 may detect the radio communication apparatus,
which has the second layer address and does not have the first
layer address, as the radio communication apparatus of the second
type.
[0047] The radio communication apparatus 10-a may include a storage
unit that stores the detected other radio communication apparatus
of the first type. Moreover, the radio communication apparatus 10-a
may include the storage unit that stores the detected radio
communication apparatus of the second type.
[0048] The forwarding address storage unit 39 stores forwarding
address information that specifies a forwarding address according
to each destination address of the packet. FIG. 4 is a diagram
illustrating a first example of the forwarding address information.
The forwarding address information may be a routing table
illustrated in FIG. 4.
[0049] The forwarding address information is stored in a data
configuration in which the destination address in the first layer,
the forwarding address in the first layer, the destination address
in the second layer, and the forwarding address in the second layer
may be stored.
[0050] For example, if the forwarding address information has a
table structure illustrated in FIG. 4, the table structure includes
a destination address column in the first layer, a forwarding
address column in the first layer, a destination address column in
the second layer, and a forwarding address column in the second
layer. For example, if the destination of the packet is the radio
communication apparatus 10-2, the forwarding address information in
a row indicated with a reference numeral 42 specifies that the
radio communication apparatus to which the packet is forwarded
after being forwarded to the radio communication apparatus 10-a is
the radio communication apparatus 10-1.
[0051] Regarding the radio communication apparatus of the first
type, the forwarding address information includes both the
destination address and the forwarding address in the first layer
and the destination address and the forwarding address in the
second layer. On the other hand, regarding the radio communication
apparatus of the second type, the forwarding address information
does not include the destination address or the forwarding address
in the first layer and includes the destination address and the
forwarding address in the second layer.
[0052] FIG. 5 is a diagram illustrating a second example of the
forwarding address information. In addition to items included in
the forwarding address information illustrated in FIG. 4, the
forwarding address information may include a forwarding layer that
is selected by the forwarding layer selecting unit 40 described
below. The forwarding layer is a layer in which a packet is
forwarded between the radio communication apparatus 10-a and the
radio communication apparatus of the forwarding address. For
example, if the forwarding address information has a table
structure illustrated in FIG. 5, the table structure has a
forwarding layer column.
[0053] For example, the forwarding address information in the row
indicated with the reference numeral 42 specifies that the packet
is forwarded in the first layer from the radio communication
apparatus 10-a to the radio communication apparatus 10-1. For
example, the forwarding address information in the row indicated
with the reference numeral 43 specifies that the packet is
forwarded in the second layer from the radio communication
apparatus 10-a to the radio communication apparatus 10-3. After
determining the forwarding layer, the forwarding layer selecting
unit 40 may store the forwarding layer in the forwarding address
storage unit 39.
[0054] With reference to FIG. 3, the forwarding layer selecting
unit 40 will be described below. Depending on whether the type of
the radio communication apparatus of the forwarding address
corresponding to the destination address is the first type or the
second type, the forwarding layer selecting unit 40 determines the
forwarding layer in which the packet, which is to be transmitted to
the destination address, is forwarded to the next forwarding
address. For example, if the radio communication apparatus of the
forwarding address is the radio communication apparatus of the
second type, the forwarding layer selecting unit 40 selects the
second layer as a forwarding layer in which the packet is forwarded
to the radio communication apparatus.
[0055] For example, if the radio communication apparatus of the
forwarding address is the radio communication apparatus of the
first type, the forwarding layer selecting unit 40 arbitrarily
selects the first layer or the second layer as the forwarding layer
in which the packet is forwarded to the radio communication
apparatus. Alternatively, for example, if the radio communication
apparatus of the forwarding address is the radio communication
apparatus of the first type, the forwarding layer selecting unit 40
may select the first layer as the forwarding layer in which the
packet is forwarded to the radio communication apparatus.
[0056] The path determining unit 41 receives the destination
address of the packet from the first forwarding unit 32 or the
second forwarding unit 34.
[0057] Alternatively, the path determining unit 41 receives the
destination address of the packet, which is transmitted from the
radio communication apparatus 10-a as the transmission source, from
an application that requests packet transmission. Based on the
forwarding address information stored in the forwarding address
storage unit 39, the path determining unit 41 determines the
forwarding address corresponding to the destination address.
[0058] The path determining unit 41 determines the forwarding
layer, which is selected by the forwarding layer selecting unit 40
to correspond to the destination address, as the forwarding layer
used to forward the packet to the forwarding address. As
illustrated in the forwarding address information in FIG. 5, the
path determining unit 41 may read out the forwarding layer from the
forwarding address storage unit 39 if the forwarding layer selected
by the forwarding layer selecting unit 40 is stored in the
forwarding address storage unit 39.
[0059] If the forwarding layer is the first layer, the path
determining unit 41 outputs the destination address and the
forwarding address to the first forwarding unit 32. The first layer
address is used as the forwarding address. If the radio
communication apparatus of the destination address is the radio
communication apparatus of the first type, the first layer address
or the second layer address may be used as the destination address.
If the radio communication apparatus of the destination address is
the radio communication apparatus of the second type, the second
layer address is used as the destination address.
[0060] The first forwarding unit 32 outputs the destination address
and the forwarding address, which are received from the path
determining unit 41, to the first layer packet generating unit 33.
The first layer packet generating unit 33 stores the destination
address and the forwarding address, which are received from the
first forwarding unit 32, in the header.
[0061] If the forwarding layer of the packet is the first layer and
the second layer address is used as the destination address, the
first layer packet generating unit 33 may store the destination
address in an extension part of the header.
[0062] FIG. 6 is an explanatory diagram of a header format of the
first layer packet. A first layer packet 100 includes a header 101
and a data 102. The header 101 includes a type 111, a subtype 112,
a forwarding address 113, a destination address 114, and an
extension part 115. The type 111 and the subtype 112 indicate a
type of packet. The forwarding address 113 is the first layer
address that indicates the forwarding address of the packet 100.
The destination address 114 is the first layer address that
indicates the destination address of the packet 100. If the
destination address in the second layer is stored in the header
101, the first layer packet generating unit 33 may store the
destination address in the extension part 115.
[0063] Embodiments will be described with reference to FIG. 3. If
the forwarding layer is the second layer, the path determining unit
41 outputs the destination address and the forwarding address to
the second forwarding unit 34. The second layer address is used as
the forwarding address and the destination address. The second
forwarding unit 34 outputs the destination address and the
forwarding address, which are received from the path determining
unit 41, to the second layer packet generating unit 35. The second
layer packet generating unit 35 stores the destination address and
the forwarding address, which are received from the second
forwarding unit 34, in the header.
[0064] FIG. 7 is a diagram illustrating a configuration example of
the radio communication apparatus 10-3 of the second type. The
processing performed by components of the radio communication
apparatus 10-3 is realized if the processor 20 executes the
forwarding program stored in the auxiliary storage device 22
illustrated in FIG. 2. FIG. 7 illustrates mainly functions related
to the explanation of the embodiment. The radio communication
apparatus 10-4 of the second type may include a configuration
equivalent to the radio communication apparatus 10-3. The other
embodiments have the similar configurations.
[0065] The radio communication apparatus 10-3 of the second type
includes a transmitting unit 50, a receiving unit 51, a forwarding
unit 52, a packet generating unit 53, a forwarding address storage
unit 54, and a path determining unit 55. The transmitting unit 50
transmits a packet to another radio communication apparatus. The
receiving unit 51 receives the packet that is transmitted from the
other radio communication apparatus. The forwarding unit 52 obtains
a data part from the received second layer packet and outputs the
data part to the packet generating unit 53.
[0066] The forwarding unit 52 performs the forwarding processing in
the second layer for forwarding the packet received by the
receiving unit 51 to the radio communication apparatus as the next
forwarding destination. Furthermore, the forwarding unit 52
performs the forwarding processing in the second layer for
forwarding the packet received from the radio communication
apparatus 10-3 as the transmission source to the radio
communication apparatus as the next forwarding destination. In the
forwarding processing, the forwarding unit 52 obtains, from the
path determining unit 55, the forwarding address in the second
layer according to the destination address of the packet.
[0067] The packet generating unit 53 generates a packet that stores
at least the destination address and the forwarding address and
stores the data obtained from the received packet by the forwarding
unit 52 or the data that is to be transmitted from the radio
communication apparatus 10-3. The generated packet is transmitted
by the transmitting unit 50.
[0068] The forwarding address storage unit 54 stores the forwarding
address information that specifies the forwarding address that is
set according to the destination address of the packet. The
forwarding address information may be a routing table, for example.
When receiving the destination address of the packet to be
forwarded from the forwarding unit 52, the path determining unit 55
determines the forwarding address corresponding to the destination
address based on the forwarding address information stored in the
forwarding address storage unit 54.
[0069] An example of the processing by the radio communication
apparatus 10-a illustrated in FIG. 3 will be described. FIG. 8 is
an explanatory diagram of the first example of the processing by
the radio communication apparatus 10-a of the first type. In the
other embodiments, operations of operations AA to AG described
below may be referred to as steps.
[0070] In Operation AA, the first address receiving unit 36
receives address information, which is related to the first layer
address of the radio communication apparatus of the first type in
the network 1, from another radio communication apparatus of the
first type. In Operation AB, the second address receiving unit 37
receives the address information, which is related to the second
layer address of the radio communication apparatus in the network
1, from the other radio communication apparatus.
[0071] In Operation AC, based on the address information received
by the first address receiving unit 36 and the second address
receiving unit 37, the detecting unit 38 detects the radio
communication apparatuses 10-1, 10-2 and 10-5 of the first type and
the radio communication apparatuses 10-3 and 10-4 of the second
type.
[0072] In Operation AD, regarding the destination address that is
stored or is scheduled to be stored in the forwarding address
storage unit 39, the forwarding layer selecting unit 40 determines
the forwarding layer in which the packet transmitted to this
destination address is transmitted to the next forwarding address.
The determined forwarding address may be stored in the forwarding
address storage unit 39.
[0073] In Operation AE, the path determining unit 41 obtains a
destination address of the packet to be transmitted. In Operation
AF, the path determining unit 41 determines the forwarding address
and the forwarding layer corresponding to the destination
address.
[0074] If the forwarding layer is the first layer, in Operation AG,
the path determining unit 41 outputs the destination address and
the forwarding address to the first forwarding unit 32. The first
forwarding unit 32 outputs the destination address and the
forwarding address to the first layer packet generating unit 33.
The first layer packet generating unit 33 generates the first layer
packet based on the received address. The transmitting unit 30
transmits the generated first layer packet.
[0075] If the forwarding layer is the second layer, in Operation
AG, the path determining unit 41 outputs the destination address
and the forwarding address to the second forwarding unit 34. The
second forwarding unit 34 outputs the destination address and the
forwarding address to the second layer packet generating unit 35.
The second layer packet generating unit 35 generates the second
layer packet based on the received address. The second layer packet
is encapsulated in the first layer packet by the first layer packet
generating unit 33 and is then transmitted by the transmitting unit
30.
[0076] FIG. 9 is an explanatory diagram of an example of
determining processing of the forwarding address and the forwarding
layer by the path determining unit 41 in Operation AF illustrated
in FIG. 8. FIG. 9 illustrates, for example, processing in a case
where the forwarding address information of the forwarding address
storage unit 39 has the table structure illustrated in FIG. 5. In
the other embodiments, operations of Operations BA to BG described
below may be referred to as steps.
[0077] In Operation BA, the path determining unit 41 determines
whether or not the destination address of the transmitted packet is
the first layer address. If the destination address is the first
layer address (Yes in Operation BA), the process goes to Operation
BB. If the destination address is not the first layer address (No
in Operation BA), the process goes to Operation BC.
[0078] In Operation BB, regarding each row of the forwarding
address information, by comparing the address stored in the
destination address column in the first layer to the destination
address of the transmitted packet, the path determining unit 41
determines the row to be referred to. The process goes to Operation
BD.
[0079] In Operation BC, regarding each row of the forwarding
address information, by comparing the address stored in the
destination address column in the second layer and the destination
address of the transmitted packet, the path determining unit 41
determines the row to be referred to. The process goes to Operation
BD.
[0080] In Operation BD, the path determining unit 41 determines the
layer, which is stored in the forwarding layer column of the row
determined by Operation BB or Operation BC, as the forwarding
layer. In Operation BE, the path determining unit 41 determines
whether or not the forwarding layer is the first layer. If the
forwarding layer is the first layer (Yes in Operation BE), the
process goes to Operation BF. If the forwarding layer is not the
first layer (No in Operation BE), the process goes to Operation
BG.
[0081] In Operation BF, the path determining unit 41 determines the
address, which is stored in the forwarding address column in the
first layer, as the forwarding address. The process ends. In
Operation BG, the path determining unit 41 determines the address,
which is stored in the forwarding address column in the second
layer, as the forwarding address. The process ends.
[0082] The radio communication apparatus of the first type
according to the present embodiment selects the forwarding layer
depending on whether the radio communication apparatus of the
forwarding address is the radio communication apparatus of the
first type or the radio communication apparatus of the second type
and then transmits the packet. Accordingly, if both the
forwardsource and the forwarding destination are the radio
communication apparatus of the first type, the packet may be
forwarded in the first layer. On the other hand, if at least either
the forward source or the forwarding destination is the radio
communication apparatus of the second type, the packet is forwarded
in the second layer. Therefore, according to the present
embodiment, the multi-hop communication in which the packet
forwards in the first layer and the second layer are performed.
[0083] Another configuration example of the radio communication
apparatus 10-a of the first type will be described. FIG. 10 is a
diagram illustrating a second configuration example of the radio
communication apparatus 10-a. The components equivalent to the
components illustrated in FIG. 3 are indicated with the similar
reference numerals. The radio communication apparatus 10-a of the
first type further includes a first address transmitting unit 60
and a second address transmitting unit 61. Another configuration of
the radio communication apparatus 10-a described below may also
include the first address transmitting unit 60 and the second
address transmitting unit 61.
[0084] The first address transmitting unit 60 reports the address
information related to the first layer address of the radio
communication apparatus 10-a to another radio communication
apparatus. Furthermore, the first address transmitting unit 60 may
report the address information, which is related to the first layer
address of the other radio communication apparatus of the first
type obtained by the radio communication apparatus 10-a after being
received by the first address receiving unit 36.
[0085] The second address transmitting unit 61 reports the address
information related to the second layer address of the radio
communication apparatus 10-a to another radio communication
apparatus. Furthermore, the second address transmitting unit 61 may
report the address information, which is related to the second
layer address of the other radio communication apparatus obtained
by the radio communication apparatus 10-a after being received by
the second address receiving unit 37.
[0086] Similarly, the radio communication apparatus 10-3 of the
second type may include an address transmitting unit that reports
the address information, which is related to the second layer
address of the radio communication apparatus 10-3, to another radio
communication apparatus. Another configurations of the radio
communication apparatus 10-3 described below may also include the
address transmitting unit.
[0087] Since each of the radio communication apparatuses 10-a, and
10-1 to 10-5 reports the address information, the radio
communication apparatus 10-a receives the first layer address and
the second layer address for the radio communication apparatus of
the first type and receives the second layer address for the radio
communication apparatus of the second type. Therefore, according to
the embodiment, the radio communication apparatus 10-a may
determine the type of each radio communication apparatus by
determining the type of the address received for the radio
communication apparatus, respectively.
[0088] Another configuration of the radio communication apparatus
10-a of the first type will be described. FIG. 11 is a diagram
illustrating a third configuration example of the radio
communication apparatus 10-a of the first type. The components
equivalent to the components illustrated in FIG. 3 are indicated
with the similar reference numerals. The radio communication
apparatus 10-a of the first type further includes a path
information receiving unit 62, a forwarding address information
generating unit 63, and a path information transmitting unit 64.
Another configuration of the radio communication apparatus 10-a
described below may also include the path information receiving
unit 62, the forwarding address information generating unit 63, and
the path information transmitting unit 64. The processing by the
forwarding layer selecting unit 40 illustrated in FIG. 3 may be
performed by the forwarding address information generating unit
63.
[0089] The path information receiving unit 62 receives path
information from the radio communication apparatuses 10-1 to 10-5.
The path information includes at least a combination of the
transmission source address of the radio communication apparatus as
the transmission source of the path information and the destination
address to which the packet may be forwarded from the radio
communication apparatus as the transmission source. The radio
communication apparatuses 10-1, 10-2, and 10-5 of the first type
may report the path information related to the first layer address
and the path information related to the second layer address. The
radio communication apparatuses 10-3 and 10-4 of the second type
may report the path information related to the second layer address
and the path information related to the second layer address.
[0090] The first address receiving unit 36 and the path information
receiving unit 62 may obtain each of the address information and
the path information from the same packet, respectively. The second
address receiving unit 37 and the path information receiving unit
62 may obtain the address information and the path information from
the same packet, respectively. The packet, which stores the address
information related to the first layer address, may store the path
information related to the first layer address. The packet, which
stores the address information related to the second layer address,
may store the path information related to the second layer
address.
[0091] The forwarding address information generating unit 63
generates the forwarding address information by determining the
transmission source address, which is combined with the destination
address, as a forwarding address. The forwarding address
information generating unit 63 stores the generated forwarding
address information in the forwarding address storage unit 39.
[0092] The path information transmitting unit 64 generates the path
information, which includes the address of the radio communication
apparatus 10-a and the destination address stored in the forwarding
address storage unit 39, and reports the path information to
another radio communication apparatus. Similarly, the radio
communication apparatus 10-3 of the second type may include a path
information transmitting unit that reports the path information,
which is related to the destination address that is forwardable by
the radio communication apparatus 10-3, to another radio
communication apparatus.
[0093] An example of the processing by the radio communication
apparatus 10-a illustrated in FIG. 11 will be described. FIG. 12 is
an explanatory diagram of the second example of the processing by
the radio communication apparatus 10-a of the first type. In other
embodiments, operations of Operations CA to CI described below may
be referred to as steps.
[0094] The processing in Operations CA to CC is equivalent to the
processing in Operations AA to AC illustrated in FIG. 8. In
Operation CD, the path information receiving unit 62 receives the
path information from the radio communication apparatuses 10-1 to
10-5. In Operation CE, the forwarding address information
generating unit 63 generates forwarding address information.
[0095] In Operation CF, regarding the destination address that is
stored or is scheduled to be stored in the forwarding address
storage unit 39, the forwarding address information generating unit
63 determines the forwarding layer in which the packet transmitted
to this destination address is forwarded to the next forwarding
address. The processing in Operations CG to CI is equivalent to
Operation AE to AG illustrated in FIG. 8.
[0096] Regarding the radio communication apparatus of the first
type, the radio communication apparatus 10-a may store the first
layer address as well as the second layer address as the forwarding
address in the forwarding address storage unit 39. According to the
present embodiment, the radio communication apparatus 10-a may
forward the packet to the radio communication apparatus of the
second type in the second layer by using the second layer address
and may forward the packet to the radio communication apparatus of
the first type in the first layer by using the first layer address.
According to the present embodiment, the multi-hop communication
network in which the packet forwards in the first layer and the
second layer are performed.
[0097] An example of generating processing of forwarding address
information will be described. FIG. 13 is an explanatory diagram of
a first example of the generating processing of the forwarding
address information. In other embodiments, operations of Operations
DA to DD described below may be referred to as steps. In the
description below, regarding M radio communication apparatuses, the
path information receiving unit 62 is assumed to obtain the path
information with the address of each radio communication apparatus
as a destination address.
[0098] In the example illustrated in FIG. 13, if there is a
plurality of forwarding addresses by which a packet may be
transmitted to the same destination address, the forwarding address
information generating unit 63 selects the forwarding address, with
which the path cost from the forwarding address to the destination
address is minimized, as the forwarding address to be used.
Therefore, the path information obtained from another radio
communication apparatus may include at least a combination of an
address of the radio communication apparatus as the transmission
source of the path information, a destination address that is
forwardable from the radio communication apparatus as the
transmission source, and the path cost between the radio
communication apparatus and the destination address.
[0099] The value of the path cost may be calculated as a function
of the processing delay of the packet forwarding, for example. The
processing delay may be a value that varies according to a
forwarding layer used to forward the packet. In addition to or
instead of the processing delay, the value of the path cost may be
calculated as a function of throughput of the number of hops, a
load of the radio communication apparatus, a radio quality of each
path, a packet of each path and/or of throughput of the packet in
the radio communication apparatus. For example, regarding to the
number of hops and the load of the radio communication apparatus, a
calculating method of the path cost may be set so that the value of
the path cost increases as the values of the number of hops and the
load of the radio communication apparatus are larger. Regarding the
radio quality and the throughput, the calculating method of the
path cost may be set so that the value of the path cost decreases
as the values of the number of hops and the load of the radio
communication apparatus are larger. For example, the value of the
path cost may be calculated by combining the value obtained by
multiplying a weight coefficient by the processing delay, the
number of hops, the load, the radio quality and/or the throughput.
The weight coefficient may vary by learning.
[0100] In Operation DA, the forwarding address information
generating unit 63 assigns a value "1" to a variable number i. In
Operation DB, from among the forwarding addresses corresponding to
an i-th destination address, the forwarding address information
generating unit 63 selects the forwarding address of the path
information, with which the past cost is minimized, as a forwarding
address to be used. In Operation DA, the forwarding address
information generating unit 63 increases the value of the variable
number i by one. In Operation DD, the forwarding address
information generating unit 63 determines whether or not the
variable number i is larger than M. If the variable number i is
larger than M (Yes in Operation DD), the process ends. If the
variable number i is equal to or smaller than M (No in Operation
DD), the process goes back to Operation DB.
[0101] According to the embodiment, the address of the radio
communication apparatus with which the path cost to the destination
address is minimized may be selected as the forwarding address.
[0102] FIG. 14 is an explanatory diagram of an example of the
generating processing of the forwarding address information and the
determining processing of the forwarding layer. In other
embodiments, operations of Operation EA to EH described below may
be referred to as steps. In the description below, regarding the M
radio communication apparatuses, the path information receiving
unit 62 is assumed to obtain the path information with an address
of each radio communication apparatus as the destination address.
The path information receiving unit 62 is assumed to obtain Ni
forwarding addresses corresponding to the i-th destination
address.
[0103] In the example illustrated in FIG. 14, by adding the path
cost from the radio communication apparatus 10-a to the forwarding
address to the path cost from each forwarding address to the
destination address, the forwarding address information generating
unit 63 calculates a path cost from the radio communication
apparatus 10-a to the destination address. The forwarding address
information generating unit 63 selects the forwarding address, with
which the calculated path cost is minimized, as the forwarding
address to be used.
[0104] The path cost from the radio communication apparatus 10-a to
the forwarding address may be a function of the processing delay of
the forwarding to the forwarding address. The processing delay of
the forwarding to the forwarding address may be a value that varies
according to the forwarding layer used for the forwarding to the
forwarding address.
[0105] For example, if the forwarding address is the first layer
address, the processing delay of the forwarding to the forwarding
address may be processing delay in a case where the forwarding
layer is the first layer. If the forwarding address is the second
layer address, the processing delay of the forwarding to the
forwarding address may be processing delay in a case where the
forwarding layer is the second layer.
[0106] If the forwarding address is selected, the forwarding
address information generating unit 63 determines that the layer
that is assumed to be the forwarding layer to the forwarding
address when the processing delay of the forwarding to the
forwarding address is determined.
[0107] In Operation EA, the forwarding address information
generating unit 63 assigns the value "1" to the variable number i.
In Operation EB, the forwarding address information generating unit
63 assigns the value "1" to a variable number j. In Operation EC,
the forwarding address information generating unit 63 calculates a
path cost from the radio communication apparatus 10-a to the i-th
destination address where the packet is forwarded to the radio
communication apparatus of a j-th forwarding address.
[0108] In Operation ED, the forwarding address information
generating unit 63 increases the value of the variable number j by
one. In Operation EE, the forwarding address information generating
unit 63 determines whether or not the variable number j is larger
than Ni. If the variable number j is larger than Ni (Yes in
Operation EE), the process goes to Operation EF. If the variable
number is equal to or smaller than Ni (No in Operation EE), the
process goes back to Operation EC.
[0109] In Operation EF, from among the forwarding addresses
obtained for the i-th destination address, the forwarding address
information generating unit 63 selects the forwarding address of
the path information, with which the path cost calculated in
Operation EC is minimized, as the forwarding address to be used.
The forwarding address information generating unit 63 determines
the forwarding layer.
[0110] In Operation EG, the forwarding address information
generating unit 63 increases the value of the variable number i by
one. In Operation EH, the forwarding address information generating
unit 63 determines whether or not the variable number i is larger
than M. If the variable number i is larger than M (Yes in Operation
EH), the process ends. If the variable number i is equal to or
smaller than M (No in Operation EH), the process goes back to
Operation EB.
[0111] According to the present embodiment, the forwarding address
and the forwarding layer may be determined so that the path cost
from the radio communication apparatus 10-a to the destination
address is minimized.
[0112] FIG. 15 is an explanatory diagram of a second example of the
generating processing of the forwarding address information. In
other embodiments, operations of Operations FA to FG described
below may be referred to as steps. In the description below, the
path information receiving unit 62 is assumed to obtain the path
information with the address of each radio communication apparatus
as the destination address regarding the M radio communication
apparatuses.
[0113] If there is a plurality of forwarding addresses with which
the path cost is minimized and the packet may arrive at the same
destination address, the forwarding address information generating
unit 63 selects the forwarding address, with which the number of
hops to the destination address is minimum, as the forwarding
address to be used. The path information received from the other
radio communication apparatus may include at least an address of
the radio communication apparatus as the transmission source of the
path information, a destination address that is forwardable from
the radio communication apparatus as the transmission source, and a
combination of the path cost from the radio communication apparatus
to the destination address and of the number of hops.
[0114] In Operation FA, the forwarding address information
generating unit 63 assigns the value "1" to the variable number i.
In Operation FB, from among the forwarding addresses obtained for
the i-th destination address, the forwarding address information
generating unit 63 selects the forwarding address of the path
information in which the path cost is minimized.
[0115] In Operation FC, the forwarding address information
generating unit 63 determines whether or not a plurality of
forwarding addresses is selected in Operation FB. If a plurality of
forwarding addresses is not selected (No in Operation FC), the
process goes to Operation FD. If a plurality of forwarding
addresses is selected (Yes in Operation FC), the process goes to
Operation FE.
[0116] In Operation FD, the forwarding address information
generating unit 63 selects the address selected in Operation FB as
the forwarding address. The process goes to Operation FF.
[0117] In Operation FE, the forwarding address information
generating unit 63 selects the forwarding address with the minimum
number of hops from among the addresses selected in Operation FB.
The process goes to Operation FF. In Operation FF, the forwarding
address information generating unit 63 increases the value of the
variable number i by one. In Operation FG, the forwarding address
information generating unit 63 determines whether or not the
variable number i is larger than M. If the variable number i is
larger than M (Yes in Operation FG), the process ends. If the
variable number i is equal to or smaller than M (No in Operation
FG), the process goes back to Operation FB.
[0118] In Operation FB illustrated in FIG. 15, the forwarding
address may be selected by calculating the path cost from the radio
communication apparatus 10-a to the destination address in the
similar way as in the processing illustrated in FIG. 14.
[0119] According to the present embodiment, if there is a plurality
of forwarding addresses with the equal path cost obtained by the
processing delay, the path with the minimum number of hops may be
selected. Therefore, the number of relay in the network may be
decreased. This may reduce a processing load of the radio
communication apparatus.
[0120] Another configuration example of the radio communication
apparatus 10-a of the first type will be described. FIG. 16 is a
diagram illustrating a fourth configuration example of the radio
communication apparatus 10-a of the first type. Components
equivalent to the components illustrated in FIG. 3 are indicated
with the similar numerals. The configuration example illustrated in
FIG. 16 describes a configuration example of the first forwarding
unit 32 and the second forwarding unit 34 illustrated in FIG. 3. A
first layer packet analysis unit 70, a forwarding layer determining
unit 71, a second layer packet analysis unit 72, a first layer
forwarding unit 73, and a second layer forwarding unit 74 described
below may be examples of the first forwarding unit 32 and the
second forwarding unit 34.
[0121] The first layer packet analysis unit 70 analyzes the first
layer packet that is received by the receiving unit 31. The
forwarding layer determining unit 71 determines the forwarding
layer of the packet that is received according to an analysis
result from the first layer packet analysis unit 70. That is, the
forwarding layer determining unit 71 determines whether the
received first layer packet stores transmission data as a data unit
or the transmission data is stored in a second layer packet that is
encapsulated in the first layer packet.
[0122] The forwarding layer determining unit 71 may determine the
forwarding layer according to a value of a header of the first
layer packet. For example, the forwarding layer determining unit 71
may determine the forwarding layer according to the value of the
type 111 and the subtype 112 of the packet 100 illustrated in FIG.
6. If the forwarding layer is the first layer, the forwarding layer
determining unit 71 outputs the data stored in the data unit 102 of
the first layer packet to the first layer forwarding unit 73 and
the second layer forwarding unit 74.
[0123] The forwarding layer determining unit 71 outputs the
destination address stored in the header to the path determining
unit 41. For example, the forwarding layer determining unit 71 may
output the first layer address stored in the destination address
114 of the packet 100 illustrated in FIG. 6 to the path determining
unit 41. Furthermore, for example, the forwarding layer determining
unit 71 may output the destination address of the second layer
address stored in the extension part 115 of the packet 100 to the
path determining unit 41. The forwarding layer determining unit 71
may determine whether or not the destination address is stored in
the extension part 115 according to the value of the type 111 and
the subtype 112.
[0124] If the forwarding layer is the second layer, the forwarding
layer determining unit 71 outputs the second layer packet that is
encapsulated in the first layer packet to the second layer packet
analysis unit 72. The second layer packet analysis unit 72 analyzes
the second layer packet and outputs the data stored in the data
unit of the second layer packet to the first layer forwarding unit
73 and the second layer forwarding unit 74. The second layer packet
analysis unit 72 outputs the destination address stored in the
header to the path determining unit 41.
[0125] The first layer forwarding unit 73 outputs, to the first
layer packet generating unit 33, the data received from the
forwarding layer determining unit 71 or the second layer packet
analysis unit 72, or the data transmitted from the radio
communication apparatus 10-a as the transmission source. The first
layer forwarding unit 73 performs the forwarding processing in the
first layer for forwarding the data that is output to the first
layer packet generating unit 33 to the radio communication
apparatus as the next forwarding destination. In the forwarding
processing, the first layer forwarding unit 73 obtains and sends
the destination address and the forwarding address of the packet to
the first layer packet generating unit 33.
[0126] The second layer forwarding unit 74 outputs, to the second
layer packet generating unit 35, the data received from the
forwarding layer determining unit 71 or the second layer packet
analysis unit 72, or the data transmitted from the radio
communication apparatus 10-a as the transmission source. The second
layer forwarding unit 74 performs the forwarding processing in the
second layer for forwarding the data output to the second layer
packet generating unit 35 to the radio deice as the next forwarding
destination. In the forwarding processing, the second layer
forwarding unit 74 obtains and sends the destination address and
the forwarding address of the packet to the second layer packet
generating unit 35.
[0127] According to the present embodiment, the forwarding layer
determining unit 71 determines the forwarding layer of the packet.
If the forwarding layer is the first layer, reception data may be
obtained from the first layer packet that is lower than the second
layer packet. As a result, the analyzing processing of the second
layer packet is omitted, so that the speed of the forwarding
processing may be increased.
[0128] All examples and conditional language recited herein are
intended for pedagogical purposes to aid the reader in
understanding the principles of the invention and the concepts
contributed by the inventor to furthering the art, and are to be
construed as being without limitation to such specifically recited
examples and conditions, nor does the organization of such examples
in the specification relate to a showing of the superiority and
inferiority of the invention. Although the embodiment(s) of the
present invention(s) has(have) been described in detail, it should
be understood that the various changes, substitutions, and
alterations could be made hereto without departing from the spirit
and scope of the invention.
* * * * *